British Journal of Nutrition

Research Article

Replacing dietary fish oil by vegetable oils has little effect on lipogenesis, lipid transport and tissue lipid uptake in rainbow trout (Oncorhynchus mykiss)

Nadège Richarda1, Sadasivam Kaushika1, Laurence Larroqueta1, Stéphane Panserata1 and Geneviève Corrazea1 c1

a1 UMR Nutrition Aquaculture Génomique, INRA Pôle Hydrobiologie, 64310 Saint Pée-sur-Nivelle, France

Abstract

In order to investigate the effects of dietary lipid sources on mechanisms involved in lipid deposition, two groups of rainbow trout were fed from first-feeding to the commercial size of 1kg (for 62 weeks) with two diets differing only by lipid source: 100% fish oil or 100% blend of vegetable oils (55% rapeseed oil, 30% palm oil, 15% linseed oil). The activities and levels of gene expression of lipogenic enzymes (fatty acid synthetase, glucose-6-phosphate dehydrogenase and malic enzyme) in liver and of lipoprotein lipase in perivisceral adipose tissue, white muscle and liver were determined. Transport of lipid was studied by determining lipid composition of plasma and lipoprotein classes. We also examined the clearance of LDL by assaying the level of LDL receptor gene expression in several tissues. Total replacement of dietary fish oil by the blend of vegetable oils did not affect growth of rainbow trout and did not modify muscle lipid content. Hepatic lipogenesis and lipid uptake in perivisceral adipose tissue, white muscle and liver were also not modified by dietary treatments. Diets containing the blend of vegetable oils induced a decrease in plasma cholesterol and LDL. In trout fed the vegetable oils diet, expression of LDL receptor gene in the liver was down-regulated.

(Received October 14 2005)

(Revised March 23 2006)

(Accepted March 24 2006)

Correspondence:

c1 *Corresponding author: Dr Geneviève Corraze, fax +33 5 59 54 51 52, email corraze@st-pee.inra.fr

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